title: Functional analysis of the AKR4C subfamily of Arabidopsis thaliana: model structures, substrate specificity, acrolein toxicity, and responses to light and [CO(2)].
abstract: In Arabidopsis thaliana, the aldo-keto reductase (AKR) family includes four enzymes (The AKR4C subfamily: AKR4C8, AKR4C9, AKR4C10, and AKR4C11). AKR4C8 and AKR4C9 might detoxify sugar-derived reactive carbonyls (RCs). We analyzed AKR4C10 and AKR4C11, and compared the enzymatic functions of the four enzymes. Modeling of protein structures based on the known structure of AKR4C9 found an (α/β)8-barrel motif in all four enzymes. Loop structures (A, B, and C) which determine substrate specificity, differed among the four. Both AKR4C10 and AKR4C11 reduced methylglyoxal. AKR4C10 reduced triose phosphates, dihydroxyacetone phosphate (DHAP), and glyceraldehydes 3-phosphate (GAP), the most efficiently of all the AKR4Cs. Acrolein, a lipid-derived RC, inactivated the four enzymes to different degrees. Expression of the AKR4C genes was induced under high-[CO2] and high light, when photosynthesis was enhanced and photosynthates accumulated in the cells. These results suggest that the AKR4C subfamily contributes to the detoxification of sugar-derived RCs in plants.
authors.affiliation: Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University.
authors.forename: Ryota
authors.initials: R
authors.lastname: Saito
authors.forename: Ginga
authors.initials: G
authors.lastname: Shimakawa
authors.forename: Akiko
authors.initials: A
authors.lastname: Nishi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Katsumi
authors.initials: K
authors.lastname: Amako
authors.forename: Amane
authors.initials: A
authors.lastname: Makino
authors.forename: Chikahiro
authors.initials: C
authors.lastname: Miyake
mesh_terms: D000171:Acrolein / Q000633:toxicity*; D000449:Aldehyde Reductase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000074408:Aldo-Keto Reductases; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology*; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008027:Light; D008958:Models, Molecular; D011487:Protein Conformation; D011765:Pyruvaldehyde / Q000494:pharmacology; D013312:Stress, Physiological; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002245:Carbon Dioxide; D011765:Pyruvaldehyde; D000171:Acrolein; D000074408:Aldo-Keto Reductases; D000449:Aldehyde Reductase